rtc: Add MCP79411 support to DS1307 rtc driver

The code is from Adrian Cox, and is patterned after similar
support in Linux (drivers/rtc/rtc-ds1307.c:1121-1135). This
chip is used on the Cyrus board from Varisys.

Signed-off-by: Andy Fleming <afleming@gmail.com>
Reviewed-by: York Sun <yorksun@freescale.com>

diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 3092de1..fc38a3f 100644 (file)
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -4,7 +4,6 @@
 #
 # SPDX-License-Identifier:     GPL-2.0+
 #
-
 #ccflags-y += -DDEBUG
 
 obj-$(CONFIG_DM_RTC) += rtc-uclass.o
@@ -37,6 +36,7 @@ obj-$(CONFIG_RTC_M48T35A) += m48t35ax.o
 obj-$(CONFIG_RTC_MAX6900) += max6900.o
 obj-$(CONFIG_RTC_MC13XXX) += mc13xxx-rtc.o
 obj-$(CONFIG_RTC_MC146818) += mc146818.o
+obj-$(CONFIG_RTC_MCP79411) += ds1307.o
 obj-$(CONFIG_MCFRTC) += mcfrtc.o
 obj-$(CONFIG_RTC_MK48T59) += mk48t59.o
 obj-$(CONFIG_RTC_MPC5200) += mpc5xxx.o

diff --git a/drivers/rtc/ds1307.c b/drivers/rtc/ds1307.c
index 03ab1a8..3be1da6 100644 (file)
--- a/drivers/rtc/ds1307.c
+++ b/drivers/rtc/ds1307.c
@@ -58,6 +58,10 @@
 #define RTC_CTL_BIT_SQWE       0x10    /* Square Wave Enable           */
 #define RTC_CTL_BIT_OUT                0x80    /* Output Control               */
 
+/* MCP7941X-specific bits */
+#define MCP7941X_BIT_ST                0x80
+#define MCP7941X_BIT_VBATEN    0x08
+
 static uchar rtc_read (uchar reg);
 static void rtc_write (uchar reg, uchar val);
 
@@ -69,6 +73,9 @@ int rtc_get (struct rtc_time *tmp)
        int rel = 0;
        uchar sec, min, hour, mday, wday, mon, year;
 
+#ifdef CONFIG_RTC_MCP79411
+read_rtc:
+#endif
        sec = rtc_read (RTC_SEC_REG_ADDR);
        min = rtc_read (RTC_MIN_REG_ADDR);
        hour = rtc_read (RTC_HR_REG_ADDR);
@@ -81,6 +88,7 @@ int rtc_get (struct rtc_time *tmp)
                "hr: %02x min: %02x sec: %02x\n",
                year, mon, mday, wday, hour, min, sec);
 
+#ifdef CONFIG_RTC_DS1307
        if (sec & RTC_SEC_BIT_CH) {
                printf ("### Warning: RTC oscillator has stopped\n");
                /* clear the CH flag */
@@ -88,6 +96,23 @@ int rtc_get (struct rtc_time *tmp)
                           rtc_read (RTC_SEC_REG_ADDR) & ~RTC_SEC_BIT_CH);
                rel = -1;
        }
+#endif
+
+#ifdef CONFIG_RTC_MCP79411
+       /* make sure that the backup battery is enabled */
+       if (!(wday & MCP7941X_BIT_VBATEN)) {
+               rtc_write(RTC_DAY_REG_ADDR,
+                         wday | MCP7941X_BIT_VBATEN);
+       }
+
+       /* clock halted?  turn it on, so clock can tick. */
+       if (!(sec & MCP7941X_BIT_ST)) {
+               rtc_write(RTC_SEC_REG_ADDR, MCP7941X_BIT_ST);
+               printf("Started RTC\n");
+               goto read_rtc;
+       }
+#endif
+
 
        tmp->tm_sec  = bcd2bin (sec & 0x7F);
        tmp->tm_min  = bcd2bin (min & 0x7F);
@@ -121,11 +146,20 @@ int rtc_set (struct rtc_time *tmp)
 
        rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100));
        rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon));
+#ifdef CONFIG_RTC_MCP79411
+       rtc_write (RTC_DAY_REG_ADDR,
+                  bin2bcd (tmp->tm_wday + 1) | MCP7941X_BIT_VBATEN);
+#else
        rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1));
+#endif
        rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday));
        rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour));
        rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min));
+#ifdef CONFIG_RTC_MCP79411
+       rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec) | MCP7941X_BIT_ST);
+#else
        rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec));
+#endif
 
        return 0;
 }